The present invention relates to a torsion bar assembly for a vehicle suspension system, and more particularly to a damper linked between a pair of the torsion bars to control vehicle roll.
Vehicles are commonly equipped with independent suspension systems which include a vibration or shock-absorbing device for absorbing road shock and other vibrations while providing a smooth and comfortable ride for the vehicle occupants. One type of shock absorbing system includes a torsion bar extending longitudinally along the length of the vehicle. One end of the torsion bar is connected to a suspension control arm while the other end is connected to the vehicle frame. The torsion bar twists with articulation of the suspension component to provide a torsional elastic resistance to the up/down or jounce/rebound movement of the suspension component. The torsion bar thereby acts as a spring to absorb vibrations from the road surface and provide particular handling qualities.
Vehicles are also commonly equipped with a stabilizer bar to increase the roll rigidity and improve the steering stability of the vehicle. Typically, the stabilizer bar is an elongated member oriented to extend laterally across the vehicle with a first and second segment extending longitudinally at each end of the central segment. The central segment of the stabilizer bar is supported for rotation about its own longitudinal axis by one or more mounting brackets which are fixed to the vehicle body or frame. Each longitudinal segment is attached to a suspension member such as a control arm of the suspension system by an end link.
When the vehicle is subjected to a lateral rolling force such as, for example, while the vehicle negotiates a turn, the longitudinal segments pivot in opposite directions with respect to the lateral axis of the central segment. As a result, torsional reaction forces are generated which act through the segments to urge the suspension members to move toward their normal position. Thus, the vehicle body will be prevented from excessive rolling or leaning to either side by the torsional resistance produced by the stabilizer bar.
Accordingly, it is desirable to provide a torsion bar suspension, which incorporates anti-roll features without the necessity of a separate stabilizer bar assembly. It is further desirable to selectively actuate the anti-roll features to provide a stiffened suspension when it is required, such as when cornering, while allowing a smooth ride when it is not required, such as during normal straight travelling.
The suspension system according to the present invention generally includes a damper assembly to provide an anti-roll capability to a vehicle torsion bar suspension system. A first and second torsion bar are respectively connected to a lower suspension link at one end. A first anchor arm is mounted to the first torsion bar and a second anchor arm is mounted to the second torsion bar. The anchor arms mount the torsion bars to a cross member of the vehicle frame.
The damper assembly is attached to each torsion bar to couple and decouple rotational motion of the torsion bars. By disengaging the damper assembly rotational motion of the torsion bars is decoupled and the torsion bars operated individually in a known manner.
The damper assembly is preferably in communication with a controller and a sensor. The sensor detects vehicle roll as the controller interprets the signals from the sensor to determine whether the damper assembly should be activated and to what degree. The activation of the damper assembly provided a roll control adjustment in response to relative movement of the suspension members.
In one embodiment the damper assembly selectively links rotational motion of the anchor arm through links. The links attach each torsion bar anchor arm to the damper assembly. By selectively linking rotational motion of the torsion bar the links and the damper assembly respond as a stabilizer bar to transfer an anti-roll force form one connecting lower suspension link to the opposite lower suspension link.
Because the torsion bar preferably absorbs impacts below a predetermined torsional force, the suspension system according to the present invention provides a smooth ride. However, when an undesirable amount of roll is detected, the damper assembly engages to stiffen the suspension system to resist roll. The anti-roll capability is thus provided when it is required, such as when cornering, while allowing a smooth ride when it is not required, such as during normal straight travelling.